The objectives of these experiments are twofold. Firt, studies will be performed to examine mechanisms by which information is processed in the cerebellar cortex. Specifically, the changes in the temporal patterning of Purkinje cell spikes resulting from the activation of cerebellar afferent pathways will be evaluated. Particular emphasis will be placed on determining the extent to which the patterning of simple spikes produced by the action of climbing fibers contributes to the responsiveness of Purkinje cells to mossy fiber inputs. Second, a separate series of studies will examine the action of dentato-bulbospinal pathways on segmental reflexes. The effects of activating this system on the stretch reflex and the cutaneomuscular reflexes will be assessed.